Funny side anecdote to the main anecdote to come: this was on my masterlist of ideas to write about as “holes in cards” and no other details which made sense at the time but then it was christmas season so past me thought even more past me was talking about christmas cards and nothing made sense anymore but now it is past that time of the year and present me figured it out.
Now for what you clicked here for.
The cards in question are playing cards, specifically discarded cards from casinos. I was at camp for a reunion with a bunch of friends and we played crazy 8 countdown about a billion times. The deck of cards had a little hole punched through the centre of each card. I knew exactly why this was a thing because my teacher told me in data management and probability in grade 12 but no one else knew and literally everyone that joined in or watched for a few seconds asked about the holes. So I got to do a lot of explaining that afternoon!!
I guess it’s not weird that nobody knew, it just never crossed my mind that they wouldn’t know. So to all 0.056 of you wondering, it’s to prevent any sort of cheating. Once a deck of cards is used, the casinos will usually get rid of them and the holes in the middle (and sometimes a corner being cut off) is how they know what has been used and what hasn’t. It’s a totally possibly thing for players to mark certain cards so that they have some advantage if that card comes up again in another round!
I think it’s kind of really wasteful but at least they let people have them (or do the casinos sell them??) after they’re done using them.